No, although that's a common misconception; it can turn out that way, but rarely does, and there's nothing of necessity wrong with a relationship in which it does not.
I was married myself for about a decade, and also painfully lonely through most of it despite being nearly never physically alone. I've operated under the impression that this had to do with the abusive nature of that relationship, and wasn't representative of any general case. Now I'm starting to wonder if I might not have been wrong about that. Certainly I still hesitate to draw any kind of general conclusion from my own experience of marriage - but I'm hearing a lot more lately from men whose experiences in this regard are similar, despite their relationships generally not appearing to be so.